1. Field of the Invention
This application relates to parallelogram boom devices for mounting agricultural implements to short wheel base tractors and adjusting implement position relative to ground during operation of the implements from the tractors. More particularly, it concerns assemblies of boom devices with short wheel base tractors for supporting spraying, cutting or like agricultural implements extending laterally from the tractors for movement close to the ground in a manner permitting such implements to: (1) have accurately controlled position relative to the ground from aboard the tractors and (2) kickback from the direction of travel in the event the implement encounters a rock, post, stump or like endangering obstruction.
2. Description of the Prior Art
There are many type operations in which a land vehicle, typically a tractor, must transit terrain with some form of implement held thereby close to the ground, but out of contact therewith. An example of such operation is the periodic spraying of liquids onto the ground from spray jets fixed to a boom carried by a tractor as disclosed in U.S. Pat. Nos. 4,206,569, 5,012,608 & 5,280,685.
It is know to use parallelogram booms to raise and lower platforms relative to ground as shown by U.S. Pat. Nos. 5,129,480 and 5,605,431. The present invention applies this parallelogram principle in unique manner to enable short wheel base tractors to laterally support agricultural implements, particularly spray units, while permitting their position relative to ground to be adjusted by an operator aboard the tractors.
Typically, prior art parallelogram booms are constructed with one or more pairs of upper and lower beams. Thus, they will have a single pair of upper and lower beams, e.g., see U.S. Pat. Nos. 5,477,930 and 5,560,130, or plural pairs of upper and lower beams, e.g., see U.S. Pat. Nos. 5,249,643, 5,577,563 and 5,584,356. In contrast, the booms of the present invention comprise two upper beams with a single lower beam thereby enabling this unique type of parallelogram boom to operate inboard of the front wheels of tractors and outboard of a front end tractor motor.